Covid-19: obesity and fatty liver increase the vulnerability of affected patients

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Obesity has been established as a risk factor for developing a severe form of Covid-19. Researchers say that people with obesity and steatohepatitis or "fatty liver disease" simultaneously are at increased risk of developing a severe form of COVID-19.

Since the beginning of the coronavirus pandemic, health authorities noted that people who were overweight or obese were at a higher risk of developing severe forms of Covid-19. For example, the Higher Council of Public Health indicates that people with a body mass index greater than 40 have a higher risk of developing a severe form of Covid-19. And according to the Ministry of Health, the link is proven by related pathologies (hypertension, diabetes, etc.) but also independently of these. Spanish researchers from the University of Santiago de Compostela carried out a study in collaboration with French researchers from Inserm, the Lille University Hospital and German researchers from the University of Lübeck, to better understand the vulnerability of this patient population.

While the Covid-19 pandemic continues to affect all regions of the world, it has been more particularly focused on people with obesity and associated nonalcoholic steatohepatitis. This pathology, also called NASH (due to non-alcoholic steatohepatitis), is a chronic disease that corresponds to an accumulation of fats in the liver (steatosis) associated with inflammation of the organ (hepatitis). Initially silent, the disease can progress, in the absence of hygienic and dietary measures, to the appearance of fibrosis (scar tissue that replaces damaged liver cells) and then cirrhosis.

The entry of the virus is different for these patients

Unrelated to excessive alcohol consumption, the disease is more common in people with obesity and / or type 2 diabetes. In this new study, researchers found in these people a higher expression of ACE2, the cellular receptor for the virus, and the Tmprss2 enzyme that facilitates the attachment of the virus and cell membranes. In fact, to infect its host, SARS-CoV-2 attaches itself to a protein present on the surface of cells, especially in the lungs: the ACE2 receptor. The latter is the center of attention because it is a key protein in Covid-19 physiology, necessary for the virus to enter host cells.

"These patients have a very efficient mechanism for the entry of the virus, which increases their vulnerability to infection," says researcher Rubén Nogueiras, who coordinated the study. Furthermore, the scientists noted that these observations do not apply to obese patients with simple steatosis (a milder stage than steatohepatitis) or to obese patients with type 2 diabetes. This suggests that SARS input factors in the liver of obese patients -CoV-2 are affected differently, although more studies with a larger panel of patients with liver damage are needed to confirm this finding.

However, with these first results published in the Journal of Hepatology, they claim to have been able to identify biomarkers in obese patients with nonalcoholic steatohepatitis, which explains this increased risk of severe disease. Note that according to Inserm, "this liver damage is now recognized as a major risk factor for cardiovascular disease." In addition to fibrosis and cirrhosis, it can progress to cancer, requiring a liver transplant. The body estimates that NASH will be the leading cause of liver transplantation in the United States for the next 5 to 10 years.

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